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Old 02-06-2008, 09:05   #1
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pounding caught on tape

Okay, check out this video from the maxing out guy on his privelege cat, (episode 2, Pirate Alley) at, crap what was it... around 4:30 it looks like waves are trying to come through the floor. In my quest to learn more about cats I'm curious, would you consider this normal? Extreme? I know the priv's reputation for being really solid... that doesn't look so solid to me. Of course the dude is sleeping through it so he must be used to it = fairly normal. That sucks. I'm sure some cat is going to get fuzzed up over this but I'm not trying to spray anyone's ego I'm just a curious cat wondering about pounding since I haven't had the ummm... privelege (sorry I'm on a roll) of of riding on one of these in a decent sea.

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Old 02-06-2008, 09:16   #2
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Perhaps you could ask the owner of the boat - he is on this forum. (Maxing Out)
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Old 02-06-2008, 09:28   #3
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sure, that's what I want.... one comment from the owner -that would be loads of help. Granted, I welcome his input but I'd also like to hear from other people with other boats. Wow, attitude on the first reply!
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Old 02-06-2008, 09:39   #4
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No - not attitude just a suggestion and a good starting point, eg I dont know what causes the massive hits, He may have been crossing the wake of a large ship - he may have been crossing a tidal bore - or that sort of pounding may be "normal" for his boat. I just sort of thought a good place to start was to ask him.
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Old 02-06-2008, 11:45   #5
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Quote:
Originally Posted by sundog View Post
. . . around 4:30 it looks like waves are trying to come through the floor.
I could be wrong, of course, but my impression is that the person holding the camera is kicking the berth to get a reaction from the dozing person.

I agree with Factor - why not ask Dave?

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Old 02-06-2008, 11:46   #6
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I could be wrong, of course, but my impression is that the person holding the camera is kicking the berth to get a reaction from the dozing person.
Would the same kicking happen if it had been a monohull?

Ok.. now I am running for the hills.
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Old 02-06-2008, 12:29   #7
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No, i think the monohull would have tipped!!! Ha Ha
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Old 02-06-2008, 12:36   #8
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I don't know what it is, but it is not the bridge deck pounding. As stated above, I suspect it is crew induced.

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Old 02-06-2008, 13:06   #9
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Ha! Definitely not bridgedeck pounding. I think Tao's right, an attempt to wake the crew.

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Old 02-06-2008, 14:53   #10
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Agreed

That is someone kicking the berth.

I've pounded and it doesn't shake to that extent. If it did, you'd probably be looking at structural damage.
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Old 03-06-2008, 00:18   #11
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I'm in with Sean, that wouldn't be a normal pounding type thing I'd say or nothing I've ever seen on a multi.

Where kicking sleeping crew is very normal, on my boat anyway and it's usually me they are aiming at
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Old 03-06-2008, 02:47   #12
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Yep - its interesting how the pounding only affects the mattress and then only one bit of it. Waiting for Dave to tell us about the kicking.
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Old 03-06-2008, 07:17   #13
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Well, that would be a relief if that's all it is, its hard to tell because I don't really know the layout of the boat or of he's sleeping in the saloon or what, after all its a qiuck shot and everything seems to have that mid-passage disorganised I don't feel like cleaning up right now look. But yeah, It looks like there would have been alarming flex occcurring if this was pounding which is why I asked. I'll have to examine the clip again....
Oh, and yes if it was a mono (or at least my old one -sold thankfully) he'd be snoozing on the floor!
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Old 03-06-2008, 22:48   #14
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That film clip was shot while I was asleep as we were getting near Aden, Yemen.

I wasn't awake, and so I can't attest to the exact sea state that was happening in the clip. The sequence shows that we are having some wave slap against the bridge deck at that particular moment.

If Exit Only is going to pound, it will happen when we are sailing to windward. On a close reach, beam reach, broad reach or run, pounding isn't a problem. Whether or not we will pound sailing to windward depends on the sea state.

I think it's helpful to differentiate between waves thumping the bridge deck from what I call real pounding.

Wave slap happens when seas trapped between the hulls give the bridgedeck a thump.

Pounding is much different. With pounding, the entire vessel is rising up and crashing down with the whole bridgedeck interacting with sea, and the boat shuddering on the impact.

Wave slap doesn't bother me or concern me. We sailed for eleven years around the world without any structural problems to our bridgedeck.

Pounding bothers me a great deal and I didn't do it very often on Exit Only. I wouldn't abuse my boat by driving it hard into seas where the bridgedeck would impact the sea in a major way.

When Robin Knox Johnson and Peter Blake won the Jules Verne Trophy sailing around the world in under eighty days in ENZA New Zealand, they had a pod/cabin between the two hulls called the "Godpod". They sailed so hard and so fast that the "Godpod" fractured from the pounding that it took. They didn't have wave slap. They had serious pounding that did structural damage.

I lived in Puerto Rico for five years, and when I sailed my 32 foot monohull to windward to Saint Thomas, I experienced pounding that made the whole hull and rigging shudder under the strain. There is no way I could have slept while pounding my way to windward.

I have two friends that sailed their monohulls from Florida to Puerto Rico, and in pounding their way to windward, they both broke bulkheads loose. In the Marquesas, I met a 37 foot heavily laid up monohull that broke all the bulkhead lose in the galley, and the galley was free floating inside the boat with the damage caused by pounding.

In my experience, pounding creates structural damage. Bridgedeck slap by waves trapped between the hulls does not create structural damage. Some people even sleep through it.

I don't think this is semantics. It's the real world of offshore cruising. If you sail to windward, sometimes you will have bridgedeck slap, and sometimes you will have pounding.

I guess one man's bridgedeck slap is another man's pounding.
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Old 04-06-2008, 00:43   #15
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Sorry I am late to the party. It's been a little busy around here just lately. Hey great vids by the way Dave. I would say that is the actual surface moving to the wave impact. I see no issues with that. It's not moving very far. It's just the slap that is making the stuff on top move and probably move further than what the actual surface was. However, Glass can flex a long way. I have seen glass hulls in powerboats move a long way and they really were being pounded. As Dave has said, pounding will eventually cause something to fail somewhere sometime. But that wasn't pounding.
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